This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This is a randomized, placebo-controlled, double blind, multicenter, two-year trial of valproate therapy at a target dose of 10-12 mg/kg/d in 300 outpatients with mild to moderate AD who lack agitation and psychosis at baseline and since onset of illness. Participants will have regular clinic visits as well as telephone contacts for assessment of behaviour, cognition, function, safety and tolerability. Valproate was selected because of its possible symptomatic efficacy for agitation in AD, known safety profile in numerous clinical populations, and in view of recent data supporting its neuroprotective potential in AD. The primary hypothesis is that chronic valproate administration to participants with AD who lack agitation and psychosis at baseline will delay the emergence of agitation and/or psychosis. An effect of this nature may have significant public health implications, for instance, by delaying instutionalization. Secondary hypotheses will addressed as well. The first of these is that chronic valproate administration to participants with AD will attenuate clinical progression of illness measured by reduced rate of cognitive or functional decline. Participants will remain in the study and be followed per protocol for two years even if they discontinue experimental treatment prematurely, in order to examine possible effects on progression of cognitive or functional decline. In addition, the safety and tolerability of chronic low dose therapy will be addresed.